(i) Field of the Invention
The invention relates broadly to the filtration of fluids. More particularly, it relates to seals in replaceable packs for filtering highly pressurized high viscosity molten polymer and extruding the filtered polymer into shaped articles such as filaments and films.
(ii) Prior Art
Packs for filtering pressurized high viscosity polymeric material and forming the filtered liquid into spun filaments are well known in the art. A pack of relatively recent design and its mode of operation is disclosed in U.S. Pat. No. 3,307,216. Typically, all such packs are assembled from a mixture of re-useable components (such as housing, lid, spinnerette) and disposable components (such as inert granular material, gaskets, and screens for supporting the inert granular material). The average time interval between replacing packs has a significant effect on both the economics of the process and the quality of the product.